An OLED refers to a light emitting phenomenon of organic semiconductor material and luminescent material through carrier injection and recombination driven by an electric field. The principle is that when an ITO transparent electrode and a metal electrode are used respectively as an anode and a cathode of a device, under a certain driven voltage, electrons and holes are injected respectively from the cathode and the anode to an electron transport layer and a hole transport layer, migrate respectively to a light emitting layer through the electron transport layer and the hole transport layer, meet in the light emitting layer to form excitons and make light emitting molecules excited, the latter emitting visible light through radiation relaxation. Radiation light may be observed from one side of the ITO, with a metal electrode film functioning as a reflective layer.
A bottleneck of producing an OLED mainly lies in a yield issue related to electrical property and reliability. The electrical property issue mainly refers to mura in a display panel. This issue may be effectively intercepted by a quality inspection system in a factory after the OLED product is completed. The reliability issue mainly refers to that a hill lock of an anode electrode film may cause a short circuit between the cathode and the anode of the OLED or result in components burning to form dark spots (DPs) when the OLED is in use. This issue may often occur after the quality inspection. Usually, when badness occurs, the product has already flowed to end-users, resulting in damage to the company's reputation.
As shown in FIG. 1, a schematic diagram of an OLED structure in related technologies is illustrated. The OLED structure includes a cathode 9, an organic light emitting layer 8 and an anode 7. The anode 7 is an anode metal reflective plane, and the cathode 9 is formed of metal having high light transmittance, such as silver, magnesium or indium tin oxide (ITO), etc. In related technologies, the anode 7 may be of a double-layer or triple-layer structure, for example, three layers of ITO/Ag/ITO, or two layers of ITO/Ag. ITO may be replaced with any transparent conductive metal as long as it may realize an anode function of the OLED. Ag forms a light reflection layer and may be replaced with any metal that has high reflectance, such as Al. However, in such an OLED structure, since a high electric field or high current is applied and a distance between the anode 7 and the cathode 9 is about 0.3 um, there exists very large relative electric field intensity. Ag/Al may be affected by the electric field so that atoms will move along a grain boundary in the direction of the current to cause a spiking phenomenon, i.e., an electro-migration phenomenon. Metal in the anode 7 will be caused to form a hill lock toward the direction of the cathode 9, which will cause a short circuit between the anode 7 and the cathode 9 of the OLED when the OLED is in use, or result in components burning to form DPs.
In addition, for example, Chinese invention patent Publication No. CN1691860A discloses a top-emitting organic electroluminescent display. As shown in FIG. 2, the top-emission organic electroluminescent display includes: a reflective layer 210a, a metal-silicide layer 210b and a transparent electrode layer 210c disposed on a substrate 200, an organic layer 230 including at least one layer of emission layer, and a second electrode layer 240. The metal-silicide layer 210b is disposed between the reflective layer 210a and the transparent electrode layer 210c to suppress electrical corrosion generated at an interface between the reflective layer 210a and the transparent electrode layer 210c and to stabilize a contact electrical resistance between the layers so that pixels with a uniform brightness may be obtained and images of high quality may be achieved.
However, in this patent, the metal-silicide layer 210b may only suppress the electrical phenomenon and forming of a metal oxide layer at an interface between the reflective layer and the transparent electrode layer. The issue that the metal material of the reflective layer 210a is affected by the electric field and the current to form a hill lock is not fundamentally solved.